Lewis Acid Mediated Synthesis of 2-Alkenenitriles Using C,N-Bis(trimethylsilyl)ketenimine and Carbonyl Compounds

Abstract
2-Substituted 2-alkenenitriles are obtained in the condensation reaction of carbonyl compounds with C,N-bis(trimethylsilyl)ketenimine in the presence of Lewis acid. The combination of tris(trimethylsilyl)ketenimine and aldehydes results in the high E-selective formation of 2-trimethylsilyl-2-alkenenitriles. Among some Lewis acids, magnesium bromide gives the best E-selectivity in the formation of 2-trimethylsilyl-2-undecenenitrile. Stereospecific protodesilylation of 2-trimethylsilyl-2-alkenenitriles in an aqueous methanol solution of potassium fluoride accomplishes a new route to (Z)-2-alkenenitriles from aldehydes.